After eluding authorities in more than a dozen states, the balding, 53-year-old man called "the Granddad Bandit" pleaded guilty Thursday to robbing two banks.

Federal officials think that the mild-mannered Michael F. Mara stole $83,800 from 26 banks in Virginia, Florida, Texas, New York and elsewhere. His plea was entered in U.S. District Court in Richmond.

Mara, of Baton Rouge, began his string of robberies at a Richmond bank in December 2008. One of his last robberies was in August in Glen Allen, Va. Mara was able to evade authorities because he didn't follow the typical patterns of a bank robber.

He never robbed "a bank in a state where he resided, and he would rarely rob the same bank in a given year," said Shawn VanSlyke, acting assistant special agent in charge of the FBI's Richmond office.

"He would travel as far as Oklahoma or Syracuse from Baton Rouge just for the sole purpose of robbing a bank," VanSlyke said.

Mara would sometimes rent cars using his own name, give a fake address and pay in cash to drive to other states to rob banks.

He would case the bank he planned to rob and look for places to park so tellers and customers wouldn't be able to see him coming or leaving, said Michael Termyn, special agent at the FBI's Richmond office.

Wearing a polo shirt and jeans or khaki pants, Mara walked calmly into banks - never covering his head or face - and handed tellers notes demanding a specific amount of money. The notes asked that the tellers not set off any alarms or ignite any dye packs. In another strange twist, authorities said, Mara would retrieve his demand notes so they couldn't become evidence. Once he had the money, he would walk away.

FBI headquarters nicknamed Mara the "Granddad Bandit" as part of a nationwide publicity campaign to find him. Authorities put up surveillance photos of Mara on nearly 2,000 digital billboards in more than 40 states, asking "Have you seen this guy?" A tipster recognized Mara and gave authorities his name.

Authorities tracked Mara to a home in Baton Rouge and arrested him after an hours-long standoff. Two handguns and a rifle were found in a car and a storage unit.

Mara kept a low profile in Baton Rouge, authorities said, and didn't appear to spend the stolen money on anything lavish. To explain his travels, he invented a tale for his neighbors and wife, whom he had recently married: He told them that he was employed by a federal emergency response agency and had to go to crisis scenes. When he returned, he prepared expense vouchers to give his stories more realism, FBI officials said.

As part of his plea agreement, Mara pleaded guilty to two counts of bank robbery in Virginia and admitted to the 24 other bank robberies in other jurisdictions. He also agreed to a 25-year sentence. He will be sentenced May 11.